Great Barrier Reef, Australia

Status: needs expert review. Figures cite GBRMPA, UNESCO, the Australian Institute of Marine Science (AIMS), and the GBRMPA Outlook Report 2024. GBRMPA and UNESCO publish slightly different area and feature counts; each figure below is attributed to its source rather than blended. A reviewer should confirm the latest AIMS condition figures and the current UNESCO World Heritage status before approval.

Overview

The Great Barrier Reef, off the coast of Queensland in northeastern Australia, is the world's largest coral reef ecosystem. The Great Barrier Reef Marine Park stretches about 2,300 km along the coast and covers approximately 344,400 km², encompassing roughly 3,000 individual reefs (GBRMPA). The UNESCO World Heritage property, inscribed in 1981 under all four natural criteria, describes the system in slightly different terms — some 2,500 reefs and over 900 islands across about 348,000 km² (UNESCO World Heritage Centre).

Key species & habitats

The reef supports exceptional marine biodiversity. GBRMPA records around 450 species of hard coral plus more than 1,000 species of soft coral, about 1,625 species of fish, six of the world's seven marine turtle species, and more than 30 species of marine mammals including whales and dolphins, as well as important dugong habitat (GBRMPA). The system spans fringing reefs, mid-shelf and outer-shelf reefs, seagrass meadows, mangroves, and continental islands, each supporting distinct communities.

Conservation status & threats

GBRMPA's Outlook Report 2024 identifies climate change as the greatest threat to the reef, with ocean warming driving repeated mass coral bleaching; coastal development, land-based run-off affecting water quality, and direct human use are additional pressures, compounded by crown-of-thorns starfish outbreaks and severe cyclones (GBRMPA Outlook Report 2024).

Mass bleaching events have been recorded in 1998, 2002, 2016, 2017, 2020, 2022 and 2024, the 2024 event being among the most spatially extensive on record (AIMS). The AIMS Long-Term Monitoring Program's 2024/25 Annual Summary reported declines in hard coral cover across all three regions of the reef following the 2024 bleaching, cyclones, and crown-of-thorns predation — a sharp reversal from the prior peak in coral cover reached in earlier years (AIMS). Reviewers should treat the most recent AIMS report as the current condition rather than the earlier record-high figures.

On the World Heritage front, the Committee at its July 2025 session did not place the reef on the List of World Heritage in Danger, instead recognising Australia's management action while ordering a full management review; the property remains under enhanced monitoring. A reviewer should confirm the operative decision as the status evolves (UNESCO World Heritage Centre).

Protected-area status & rules

The reef is managed by the Great Barrier Reef Marine Park Authority within a World Heritage property, under a zoning system. Marine National Park (Green) Zones are no-take areas where fishing and collecting are prohibited without a permit. Per GBRMPA's Responsible Reef Practices:

• Do not touch, collect, or take coral, including dead coral, without a Marine Parks permit.
• Anchor in sand and use moorings rather than anchoring on coral; observe no-anchoring areas.
• Know your zone before fishing or collecting, and follow Green Zone no-take rules.

The Eye on the Reef program lets visitors and operators check zoning and report reef health and incidents, feeding citizen-science data back to managers (GBRMPA).

How to visit responsibly

• Check the marine park zoning for any site before fishing, collecting, or anchoring, and respect no-take Green Zones.
• Use reef moorings; never anchor on coral. Maintain buoyancy and distance so fins and hands do not contact coral.
• Choose operators certified in responsible reef practices, and report bleaching or damage through Eye on the Reef rather than handling affected coral.
• Recognise that the overriding pressure is thermal: minimising local impact matters, but the reef's trajectory is set chiefly by ocean warming.

How you can help

• Reduce your carbon footprint — GBRMPA identifies climate change as the greatest threat, and ocean warming drives the bleaching events degrading the reef.
• Support catchment and water-quality programs that reduce land-based run-off.
• Contribute observations through Eye on the Reef and back crown-of-thorns control and reef-restoration efforts.